# Multimode and Long-Lived Quantum Correlations Between Photons and Spins in a Crystal

 Authors: Cyril Laplane, Pierre Jobez, Jean Etesse, Nicolas Gisin, Mikael Afzelius Phys. Rev. Lett. 118, 210501 (2017) http://dx.doi.org/10.1103/PhysRevLett.118.210501 The realization of quantum networks and quantum repeaters remains an outstanding challenge in quantum communication. These rely on the entanglement of remote matter systems, which in turn requires the creation of quantum correlations between a single photon and a matter system. A practical way to establish such correlations is via spontaneous Raman scattering in atomic ensembles, known as the Duan-Lukin-Cirac-Zoller (DLCZ) scheme. However, time multiplexing is inherently difficult using this method, which leads to low communication rates even in theory. Moreover, it is desirable to find solid-state ensembles where such matter-photon correlations could be generated. Here we demonstrate quantum correlations between a single photon and a spin excitation in up to 12 temporal modes, in a 151Eu3+-doped Y2SiO5 crystal, using a novel DLCZ approach that is inherently multimode. After a storage time of 1 ms, the spin excitation is converted into a second photon. The quantum correlation of the generated photon pair is verified by violating a Cauchy-Schwarz inequality. Our results show that solid-state rare-earth-ion-doped crystals could be used to generate remote multimode entanglement, an important resource for future quantum networks. laplane2017a.pdf

# BibTeX Source

@Article{PhysRevLett.118.210501,
title =        "Multimode and Long-Lived Quantum Correlations Between Photons and Spins in a
Crystal",
author =       "Cyril Laplane and Pierre Jobez and Jean Etesse and Nicolas Gisin and Mikael
Afzelius",
journal =      "Phys. Rev. Lett.",
volume =       "118",
issue =        "21",
pages =        "210501",
numpages =     "5",
year =         "2017",
month =        may,
publisher =    "American Physical Society",
doi =          "10.1103/PhysRevLett.118.210501",
abstract =     "The realization of quantum networks and quantum repeaters remains an outstanding
challenge in quantum communication. These rely on the entanglement of remote matter
systems, which in turn requires the creation of quantum correlations between a
single photon and a matter system. A practical way to establish such correlations
is via spontaneous Raman scattering in atomic ensembles, known as the
Duan-Lukin-Cirac-Zoller (DLCZ) scheme. However, time multiplexing is inherently
difficult using this method, which leads to low communication rates even in theory.
Moreover, it is desirable to find solid-state ensembles where such matter-photon
correlations could be generated. Here we demonstrate quantum correlations between a
single photon and a spin excitation in up to 12 temporal modes, in a 151Eu3+-doped
Y2SiO5 crystal, using a novel DLCZ approach that is inherently multimode. After a
storage time of 1 ms, the spin excitation is converted into a second photon. The
quantum correlation of the generated photon pair is verified by violating a
Cauchy-Schwarz inequality. Our results show that solid-state rare-earth-ion-doped
crystals could be used to generate remote multimode entanglement, an important
resource for future quantum networks.",
}